Audio signal processing method, audio signal processing apparatus, Hi-Fi video apparatus, digital video apparatus and 8 mm video apparatus

ABSTRACT

An audio signal processing method for repairing an anomalous state such as noise, a discontinuity, and a break of sound, comprising detecting the anomalous state of an audio signal, deleting the audio signal in the anomalous segment, deducing the correct audio signal by referring to the waveform of the audio signal before and after the deleted segment, generating a repair signal for repairing the signal in the deleted segment based on the deduced result, inserting the repair signal into the deleted segment, and connecting it to the audio signal before and after the deleted segment.

RELATED APPLICATION DATA

This application is a continuation of U.S. Ser. No. 09/734,512, filedDec. 11, 2000, now U.S. Pat. No. 6,961,513 incorporated herein byreference, which claims priority to Japanese Application No. P11-358117,filed Dec. 16, 1999 and Japanese Application No. P11-358118, filed Dec.16, 1999, all of which are incorporated herein by reference to theextent permitted by law.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for processingan audio signal and apparatuses using the same. More particularly, thepresent invention relates to a method an apparatus for eliminating shotnoise, discontinuity, and a data loss and repairing an audio signal andapparatuses using the same.

The present invention is applied to compensation for loss of soundoccurring when performing high speed reproduction (special reproduction)etc. in a receiver of a broadcasted audio signal, a reproduction systemof an audio signal recorded on a magnetic tape, an optical disk, anopto-magnetic disk, or the like, and a decoding system of a digitallytransmitted audio signal, for example, a Hi-Fi video apparatus, adigital video apparatus (digital video signal recording and/orreproducing apparatus), and an 8 mm video apparatus.

2. Description of the Related Art

In a receiver of a broadcasted audio signal, a reproduction system of anaudio signal recorded on a magnetic tape, optical disk, opto-magneticdisk, or the like, a decoder of a digitally transmitted audio signal,etc., there is sometimes shot noise, discontinuity of data, and dataloss—frequently occurrences in a communication path, a recordingapparatus, a reproducing apparatus, packet communication, etc.

Such noise is generated everywhere due to, for example, noise generatedin the air or in the apparatus, scratches or dust on the magnetic tape,scratches or dust on the optical disk, scratches or dust on an analogrecord disk, and reading error of the reproducing apparatus. Such noisecauses a remarkably incongruity in sound.

In the past, when such noise and discontinuity occurred, the method ofreducing the noise component by a low pass filter, a high pass filter,or the like and the method of replacing segments of data loss by thesignal before and after them (Japanese Unexamined Patent Publication(Kokai) No. 9-274772) have been tried. Further, particularly, whendigital data is used, the noise and the discontinuity have been reducedby means of prevalue hold, mean value interpolation, attenuationinterpolation, muting, or the like

However, a frequency filter distorts the normal signal portion as welland further is not that effective in elimination of short time and widefrequency band signals such as shot noise and discontinuity.

Further, prevalue hold and mean value interpolation are problematic inthat a discontinuity newly occurs with the preceding and following data,so incongruity in sound is newly caused.

As concrete audio signal processing apparatuses, related art of Hi-Fivideo apparatuses, digital video signal recording and/or reproducingapparatuses, 8 mm video apparatuses, etc. and problems thereof will beexplained.

A Hi-Fi video apparatus using a magnetic tape has, as illustrated inFIG. 3, two tracks, that is, a fixed audio track and a Hi-Fi audiotrack, as tracks for recording an audio signal on the magnetic tape.

The fixed track is oriented parallel to the tape running direction andis provided at a position independent from the video signal track. It isscanned by a fixed head 17 illustrated in FIG. 2 and has a low dynamicrange, a low frequency range, and a high noise level in structure. It isusually used for only monaural recording.

The Hi-Fi track is helically scanned by a rotary head drum 16illustrated in FIG. 2 and records an audio signal by deep layerrecording etc.* at the same position as the video track. It has a highdynamic range, a high frequency range, and a low noise level and isusually used for stereo recording.

In general, the Hi-Fi track is used for high quality sound reproductionat the time of normal reproduction, while the fixed track is used forlow quality sound reproduction at the time of special (high speed)reproduction.

For example, Japanese Unexamined Patent Publication (Kokai) No. 5-292449discloses a method of reproducing a video signal recorded on a videotrack at an (N+1)/N speed. However, the fixed track has to be used forreproduction of the audio signal. The reason for this is that, as shownin FIG. 4, at the time of special reproduction, the rotary head scans aplurality of Hi-Fi tracks by obliquely traversing them (helically scansthem), so the video signal can be reproduced as one image by combining aplurality of fields, but, in contrast, noise due to discontinuity of thescanning of the rotary head frequently occurs in the audio signal tocause remarkable incongruity in sound, so the Hi-Fi track cannot beused. Therefore, the Hi-Fi track is not used. Instead, the fixed trackis used using the fixed head 17—which is free from the problem ofdiscontinuous scanning of the head.

In high speed reproduction for a head search or the like, in the case ofhigh speed reproduction at 2× speed or more, a high quality of sound isnot always required, so there is little problem.

However, when trying to save time while fully viewing and listening tothe content by reproduction at a slightly high speed, for example, a1.2× speed, the quality of sound when reproducing the audio signalrecorded on the fixed audio track, which is fixed to such high speedreproduction, is insufficient. Therefore, utilization of the Hi-Fi audiotrack providing a high quality audio signal has been demanded.

In a digital video signal recording and/or reproducing apparatus using amagnetic tape, when giving as an example the format of for example aconsumer digital video system, as shown in FIG. 24, a helical trackinclined with respect to the tape running direction is divided intounits of blocks. A compressed and encoded video signal is recorded atthe center, while the audio signal and auxiliary signals are recorded onthe two sides.

At the time of high speed reproduction in the digital video signalrecording and/or reproducing apparatus, as shown in FIG. 25, a skip inthe middle of a track is avoided by an auto-tracking mechanism. However,the discontinuity of the audio signal occurring due to the tracks notbeing read at the time of high speed reproduction causes a remarkableincongruity in sound at the time of reproduction in the same way as thecase of a Hi-Fi video apparatus.

As the audio signal processing for reducing such incongruity in sound atthe time of high speed reproduction in such a digital video signalrecording and/or reproducing apparatus, various countermeasures havebeen considered heretofore. Examples thereof will be explained below.

(1) The method of permitting the discontinuity and connecting the signalas it is (Japanese Patent No. 2,687.706),

(2) The method of muting the discontinuous portion,

(3) The method of changing the speed of the rotary head to match thetape running speed and reading all data (Japanese Patent No. 2,766,065),

(4) The method of replacing the lost portions of the audio signal by thedata before and after it (Japanese Unexamined Patent Publication (Kokai)No. 9-274772), and

(5) The method of connecting the audio signal before and after a lostportion by a cross fading (Japanese Patent No. 2,737,182).

With the methods of (1) and (2), however, discontinuity or mutingperiodically occurs, so the incongruity cannot be solved.

With the method of (3), the apparatus becomes complex and further thedata becomes too large, so time compression and sampling rate conversionare necessary. As a result, a new incongruity in sound such as a rise insound pitch is caused.

With the method of (4), although there is the effect of reduction of theincongruity without muting the frames from which data has been lost,discontinuity still occurs before and after the replaced data.Accordingly, there is a problem of how to repair the audio signalwithout incongruity.

With the method of (5), although the discontinuity is solved by a crossfading of the data before and after the discontinuity, this is donewithout considering waveform periodicity etc., so there is a problem inthat incongruity due to mismatch of phase is newly caused.

An 8 mm video apparatus recording and reproducing an audio signal by arotary head suffers from problems similar to those described above.

A magnetic recording apparatus using not magnetic tape, but a fixed diskis excellent in random accessability, so the problem such as the skip ofa track due to the physical structure described above does not occur.However, a certain time is required for reading data. Therefore, at thetime of high speed reproduction, it is sometimes necessary todeliberately reduce the number of read fields. At this time, the problemof discontinuity of sound similar to the above arises.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an audio signalprocessing method and apparatus for eliminating shot noise and smoothlyinterpolating discontinuity of an audio signal without distorting anormal portion and thereby reducing the incongruity in sound andapparatuses using the same.

Another object of the present invention is to provide a method anapparatus for processing a reproduced audio signal to an audio signalfree from incongruity in sound at the time of high speed reproduction ina magnetic tape type audio signal reproducing apparatus reproducing anaudio signal recorded by helical scanning of a rotary audio head on amagnetic tape such as a Hi-Fi video apparatus, digital video signalrecording and/or reproducing apparatus, and 8 mm video apparatus andsuch apparatuses using the same.

Still another object of the present invention is to provide a method andapparatus for processing a reproduced audio signal to an audio signalfree from incongruity in sound at the time of high speed reproduction ina rotary audio signal reproducing apparatus reproducing an audio signalrecorded on a substantially randomly accessable rotary recording mediumsuch as a magnetic disk, optical disk, and opto-magnetic disk and suchapparatuses using the same.

According to a first aspect of the present invention, there is providedan audio signal processing method comprising the steps of deleting anaudio signal in an anomalous segment, deducing a correct audio signal byreferring to the waveform of the audio signal before and after thedeleted segment, generating a repair signal for repairing the signal ofthe deleted segment based on the deduced result, inserting the repairsignal into the deleted segment, and connecting the same with the audiosignal before and after the deleted segment.

Preferably, the method further comprises detecting an anomalous state ofthe audio signal and performing the above processing when detecting theanomalous state.

Preferably, the method further comprises evaluating the similarity ofsignal waveform before and after the deleted segment in the step ofdeducing the audio signal, generating the repair signal by the waveformwith the greatest similarity in the step of generating the repairsignal, and smoothly connecting the inserted repair signal and the audiosignal before and after the deleted segment in the step of connectingthe audio signal.

Further preferably, the method further comprises measuring andsuccessively adding a time discrepancy between a segment with thewaveform connected by using the repair signal and a segment with theanomalous signal deleted therefrom and performing the processing of thededucing step, repair signal generation step, and signal connection stepagain when a sum of the time discrepancy exceeds a constant timediscrepancy so as to adjust the time discrepancy.

Preferably, the method further comprises calculating a correlationfunction for the audio signal before and after the deleted segment inthe step of deducing the audio signal and evaluating the similarity byreferring to the calculated correlation function.

Alternatively, the method further comprises calculating a correlationfunction for the audio signal before and after the deleted segment inthe step of generating the repair signal and cross fading the audiosignal or cross fading the audio signal before and after the deletedsegment to smoothly connect it in the step of connecting the audiosignal.

The method may detect the anomalous state by detecting skip scanning ofa reading means when reading an audio signal from a recording medium.

Alternatively, it may detect the anomalous state by statisticallyprocessing the audio signal and detecting a sudden fluctuation in theaudio signal.

According to a second aspect of the present invention, there is providedan audio signal processing method comprising the steps of deleting anaudio signal of a noise segment of noise and discontinuity due to shotnoise superposed on the audio signal or a signal skip, evaluating asimilarity of signal waveform before and after the noise segment, andsmoothly connecting waveforms to give a maximum similarity.

According to a third aspect of the present invention, there is providedan audio signal processing apparatus utilizing the above audio signalprocessing methods.

The audio signal processing apparatus comprises a signal deleting meansfor deleting an audio signal of an anomalous segment, a deducing meansfor deducing a correct audio signal by referring to waveform of theaudio signal before and after the deleted segment, a repair signalgenerating means for generating a repair signal for repairing the signalof the deleted segment based on the deduced result, and a signalconnecting means for inserting the repair signal into the deletedsegment and connecting the same with the audio signal before and afterthe deleted segment.

The audio signal processing apparatus may further comprise an anomalydetecting means for detecting an anomalous state of the audio signal andperforming the processing when detecting the anomalous state. Theanomalous state is generated at for example a track skip at the time ofhigh speed reproduction or switching of the rotary head in a Hi-Fi videoapparatus.

When detecting the anomalous state, the apparatus deletes the audiosignal of the anomalous state portion. Then, considering the continuityof the audio signal, it deduces the audio signal of the deleted portionby referring to the audio signal before and after the deleted portion.Next, it generates a repair signal corresponding to the correct audiosignal. Finally, it inserts the repair signal into the deleted segmentand connects it to the audio signal before and after the deletion.

The present invention may be applied to a Hi-Fi video apparatus, digitalvideo apparatus (digital video signal recording and/or reproducingapparatus), 8 mm video apparatus, magnetic disk apparatus, etc.

As a result, even in the case of high speed reproduction in for examplea Hi-Fi video apparatus and 8 mm video apparatus, a high quality Hi-Fiaudio signal can be reproduced. Further, pulse noise generated at thetime of high speed reproduction of a digital video apparatus is reduced,the incongruity in sound is reduced, and high quality reproductionbecomes possible.

For example, in a Hi-Fi video apparatus, even when trying to save timewhile fully viewing and listening to the content by reproduction at 1.2×speed, a high quality audio signal can be reproduced. In a magnetic diskapparatus, it becomes possible to obtain a greater margin in the accesstime and therefore perform time division processing with other taskswithout exceeding the limit of the access time.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome clearer from the following description of the preferredembodiments given with reference to the attached drawings, in which:

FIG. 1 is a schematic view of the configuration of a first example of aHi-Fi video apparatus according to an embodiment of the presentinvention;

FIG. 2 is a schematic view of tape running and a rotary head of theHi-Fi video apparatus illustrated in FIG. 1;

FIG. 3 is a view of a track structure of a tape recording surface of amagnetic tape in the Hi-Fi video apparatus illustrated in FIG. 1;

FIG. 4 is a view of a trace of a head when reproducing a video Hi-Fiaudio track of the magnetic tape illustrated in FIG. 3 at the time ofhigh speed reproduction;

FIG. 5 is a view of details of the track structure of the magnetic tapeof the Hi-Fi video apparatus illustrated in FIG. 1 and a head trace atthe time of high speed reproduction;

FIG. 6 is a flow chart of an operation of a track skip detectorillustrated in FIG. 1;

FIGS. 7A to 7C are views of a rotary head switch operation in a Hi-Fivideo apparatus, in which FIG. 7A is a view of a recording track, a usedhead, and an azimuth thereof, FIG. 7B is a view of a rotary head pulseand a track skip pulse at the time of high speed reproduction, and FIG.7C is a view of a reproduction track, a used head, and the azimuththereof by a head switch operation;

FIG. 8 is a flow chart of the rotary head switch operation in a headswitch illustrated in FIG. 1;

FIG. 9 is a view of the configuration of a waveform connectorillustrated in FIG. 1;

FIG. 10 is a view of the configuration of a signal buffer illustrated inFIG. 9;

FIG. 11 is a flow chart of the operation of a signal processor in thewaveform connector illustrated in FIG. 9;

FIG. 12 is a waveform diagram of an input signal subjected to the signalprocessing in the waveform connector of FIG. 9;

FIG. 13 is a waveform diagram of a signal with an anomalous portiondeleted therefrom in the waveform connector of FIG. 9;

FIG. 14 is a signal waveform diagram for explaining a method ofdetecting similar waveforms in the waveform connector of FIG. 9;

FIG. 15 is a signal waveform diagram for explaining a method ofconnecting the waveform in the waveform connector of FIG. 9;

FIG. 16 is a signal waveform diagram for explaining a second method ofdetecting similar waveforms in the waveform connector of FIG. 9;

FIG. 17 is a signal waveform diagram for explaining a method of shiftingwaveform signals for connecting the waveform in the waveform connectorof FIG. 9;

FIG. 18 is a signal waveform diagram for explaining a method ofpreparing a similar waveform for connecting the waveform in the waveformconnector of FIG. 9 and inserting the same;

FIG. 19 is a schematic view of the configuration of a second example ofa Hi-Fi video apparatus according to an embodiment of the presentinvention;

FIG. 20 is a view of the configuration of the waveform connector in FIG.19;

FIG. 21 is a view of the configuration of an anomaly detector in FIG.20;

FIG. 22 is a flow chart of the operation of a signal processor in thewaveform connector illustrated in FIG. 19;

FIG. 23 is a view of the configuration of a digital video signalrecording and/or reproducing apparatus according to a second embodimentof the present invention;

FIG. 24 is a view of a track structure of a recording surface of aconsumer use digital video tape in FIG. 23;

FIG. 25 is a view of a head scanning trace at the time of high speedreproduction of the digital video signal recording and/or reproducingapparatus of FIG. 23;

FIG. 26 is a view of the configuration of the waveform connectorillustrated in FIG. 23;

FIG. 27 is a view of the track structure of an 8 mm video tape accordingto a third embodiment of the present invention;

FIG. 28 is a view of the configuration of a magnetic disk apparatusaccording to a fourth embodiment of the present invention; and

FIGS. 29A, 29B, 29G, and 29D are graphs of the operation timing of themagnetic disk apparatus of FIG. 28.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, preferred embodiments of the audio signal processing method andapparatus of the present invention will be explained.

Note that the gist of the present invention resides in the processingfor repairing anomaly of an audio signal—not the recording of the audiosignal. Similarly, processing of a video signals is not its gist.Accordingly, so far as they do not particularly relate to the presentinvention, the recording of an audio signal and the processing of avideo signal will not be referred to.

However, the present invention is not limited to only an audio signalreproducing apparatus. The present invention can also be applied to adigital video signal recording and/or reproducing apparatus using theaudio signal processing method and apparatus of the present inventionand an audio signal and/or video signal recording and/or reproducingapparatus using the audio signal processing method and apparatus of thepresent invention.

FIRST EXAMPLE OF HI-FI VIDEO APPARATUS

As a first embodiment of use of the audio signal processing apparatus ofthe present invention, a first example of a Hi-Fi video apparatus willbe explained by referring to FIG. 1 to FIG. 8.

FIG. 1 is a view of the configuration of a Hi-Fi video apparatusaccording to the first embodiment of the present invention, while FIG. 2is a schematic view of tape running and a rotary head of the Hi-Fi videoapparatus illustrated in FIG. 1.

The Hi-Fi video apparatus 1 has a rotary head controller 11, a headswitch 12, a track skip detector 13, an FM demodulator 14, a waveformconnector 15, a rotary head drum 16 with rotary heads A1 and A2 and B1and B2 mounted thereon, a fixed head 17, a not illustrated rotationdrive controller of the rotary head drum 16, a not illustrated runningdrive controller of a magnetic tape 18, a not illustrated audio signalreproducing apparatus, and a not illustrated video signal reproducingapparatus.

The rotation drive controller of the rotary head drum 16, the runningdrive controller of the magnetic tape 18, the audio signal reproducingapparatus, and the video signal reproducing apparatus are not directlyrelated to the present invention, so the illustration was omitted, butthey are similar to those in the well known apparatuses.

The Hi-Fi video apparatus 1 records an audio signal and a video signalon the magnetic tape 18 and reproduces the audio signal and the videosignal recorded on the magnetic tape 18 by helical scanning using therotary head drum 16 with the rotary heads A1, A2, B1, and B2.

FIG. 3 is a view of a track structure of the tape recording surface inthe Hi-Fi video apparatus.

A pair of rotary heads A1 and A2 and a pair of rotary heads B1 and B2shown in FIG. 1 are arranged, as shown in FIG. 2, at positionsrotationally symmetric with respect to a center O of the rotary headdrum 16, that is, facing positions 180 degrees apart, at the rotary headdrum 16. The rotary heads A1 and A2 are arranged at adjacent positionsand have azimuth angles reverse to each other. Also, the rotary heads B1and B2 are similarly arranged at adjacent positions and have azimuthangles reverse to each other. The rotary heads A1 and B2 and the rotaryheads A2 and B1 are given the same azimuth angles. This arrangement iscalled a double azimuth type. As will be explained later, such aconfiguration is employed at the time of high speed reproduction so thatthe reproduction head scans the recorded track at a different azimuthangle from that at the time of recording.

The rotary head controller 11, head switch 12, track skip detector 13,FM demodulator 14, and the waveform connector 15 will be brieflyexplained next.

The rotary head controller 11 controls a not illustrated drive system soas to rotate the rotary head drum 16 at a designated speed. At the sametime, it generates a rotary head pulse S11 whenever the rotary heads A1and B1 pass an origin C illustrated in FIG. 2 and outputs it to the headswitch 12.

The track skip detector 13 compares the signal levels of the signalsobtained from the rotary heads A1, A2, B1, and B2 to monitor if therotary head having the maximum signal level changes from the rotary headA1 to A2, from the rotary head A2 to A1, from the rotary head B1 to B2,or from the rotary head B2 to B1. Where it detects a change of therotary heads, it concludes there was a track skip, generates a trackskip pulse S13 at that time, and outputs the track skip pulse to thehead switch 12 and the waveform connector 15.

The head switch 12 receives as its inputs the detection signals of therotary heads A1, A2, B1, and B2 and selects one of the detection signalsof the rotary heads A1, A2, B1, and B2 in accordance with the rotaryhead pulse S11 from the rotary head controller 11 and the track skippulse S13 from the track skip detector 13.

The rotary head pulse S11 output from the rotary head controller 11 isthe signal detecting the passage of the rotary head drum 16 through theposition C, so indicates one revolution of the rotary head drum 16. Itis also the signal for discriminating the positions of the pair ofrotary heads A1 and A2 and the pair of rotary heads B1 and B2. On theother hand, the track skip pulse S13 detected at the track skip detector13 is a signal indicating that the rotary heads A1 and A2 or the rotaryheads B1 and B2 skipped a track in the magnetic tape 18. Accordingly,the head switch 12 switches between the rotary heads An and B by therotary head pulse S11 from the rotary head controller 11 and switchesbetween the rotary heads 1 and 2 by the track skip pulse S13 from thetrack skip detector 13. Note that, the rotary head A indicates therotary heads A1 and A2, and similarly the rotary head B indicates therotary heads B1 and B2. Further, the rotary head 1 indicates the rotaryheads A1 and B1, and the rotary head 2 indicates the rotary heads A2 andB2.

The FM demodulator 14 demodulates the audio signal selected at the headswitch 12 and inputs the same to the waveform connector 15.

The waveform connector 15 smoothly connects the signal FM demodulated atthe FM demodulator 14 while maintaining the continuity and outputs thesame as the repaired audio signal to deal with the anomalous state suchas the discontinuity of the signal or skip or noise from the timingbased on the track skip pulse S13 detected at the track skip detector13.

Details of the high speed reproduction operation of the Hi-Fi videoapparatus 1 will be explained next.

Track Skip Detector

FIG. 3 is a view of the track structure of the tape recording surface ofthe magnetic tape 18 of a Hi-Fi video apparatus.

FIG. 4 is a view of the trace of the head at the time of high speedreproduction of the video Hi-Fi audio track of the magnetic tape 18illustrated in FIG. 3.

FIG. 5 is a view of the track structure of the magnetic tape 18 and thehead trace at the time of high speed reproduction. Symbols R1 to R7shown in FIG. 5 are track numbers attached for convenience for theexplanation of the present embodiment, while symbols Q1 to Q7 arescanning numbers attached for convenience for the explanation of thepresent embodiment

The track skip detector detects the time of occurrence of a track skipindicated by a mark O at the time of high speed reproduction as shown inFIG. 4 and FIG. 5, generates a track skip pulse S13 at that time, andoutputs the track skip pulse S13 to the head switch 12 and the waveformconnector 15.

The principle of generation the track skip pulse S13 in the track skipdetector 13 will be explained next.

In the helical scanning of the Hi-Fi video tape shown in FIG. 3, aspartially indicated by hatching in the track, the recording azimuthangles of the adjoining tracks are different. In the case of for examplea VHS Hi-Fi video, an angle of +30 degrees is given for every track.When head scanning over a plurality of tracks as shown in FIG. 4 andFIG. 5, the azimuth angle of the recording surface becomes reverse atthe time when the track skip indicated by the mark O occurs, the angleof the head in use loses compatibility, and the other head forming thepair becomes compatible. Due to this, the magnitudes of the outputlevels of the paired (A1 and A2 and B1 and B2) heads are switched witheach other.

FIG. 6 is a flow chart of the processing of the track skip detector 13.

The track skip detector 13 follows the above principle of detection andrefers to the rotary head pulse S11 from the rotary head controller 11to judge whether the rotary heads A1 and A2 are located at the tapesurface of the magnetic tape 18 or the rotary heads B1 and B2 arelocated at the tape surface of the magnetic tape 18 (S1). When therotary heads A1 and A2 are located at the tape surface of the magnetictape 18, it compares the signal levels of the rotary heads A1 and A2.When detecting that they are replaced with heads outputting signalshaving a larger level (S2, S4: S2, S4), it generates the track skippulse S13 (S5). Similarly, when the rotary heads B1 and B2 are locatedon the tape surface of the magnetic tape 18, it compares the signallevels of the rotary heads B1 and B2. When detecting that they arereplaced with heads outputting signals having a larger level (S6 to S8),it generates the track skip pulse S13 (S5)

FIGS. 7A to 7C are graphs showing the rotary head switch operation.

The track skip pulse S13 may be a single pulse in the head switch 12 asillustrated in FIG. 7B. However, the waveform connector 15 explainedlater requires the time when the track skip was generated. Therefore,the track skip pulse S13 to be given to the head switch 12 is made aone-pulse signal as illustrated in FIG. 7B. On the other hand, as thetrack skip pulse S13 to be given to the waveform connector 15, otherthan the one-pulse signal, the track skip generation time is informed.Alternatively, only a one-pulse signal is given to the waveformconnector 15 and the time when receiving the track skip pulse S13 isstored in the waveform connector 15. In the present embodiment, as willbe explained later by referring to FIG. 9 and FIG. 10, the case isillustrated where, when one pulse of the track skip pulse S13 issupplied from the track skip detector 13 to the waveform connector 15, abuffer controller 1551 in the waveform connector 15 sets the positionanomaly flag indicating that time in a signal buffer 152.

Rotary Head Switch

The rotary head switch 12 receives as its input the rotary head pulseS11 output from the rotary head controller 11 and the track skip pulseS13 output from the track skip detector 13 and switches the detectionsignals of the reproduction heads A1, A2, B1, and B2.

At the time of recording, as illustrated in FIG. 7A, the data isrecorded by azimuth angles alternating for every track by using therotary heads A1 and B1 having reverse azimuths located at facingpositions. Namely, as illustrated in FIG. 5, the audio signal isrecorded on a track R1 by the rotary head A1 with a positive azimuth(for example +30 degrees), and audio signal is recorded on a track R2 bythe rotary head B1 with a negative azimuth (for example −30 degrees).The audio signal is then alternately recorded in a similar way to thatdescribed above. Note that an explanation of the recording of the videosignal is omitted.

At the time of normal reproduction of the recorded audio signal, in thesame way as the time of recording explained above by referring to FIG.7A, the data is reproduced by azimuth angles alternating for every trackby using the rotary heads A1 and B1 having the reverse azimuths locatedat facing positions.

At the time of recording in the Hi-Fi video apparatus 1 of the presentembodiment, the operation at the time of normal reproduction is similarto the operation of the usual well known Hi-Fi video apparatus.

At the time of high speed reproduction, as illustrated in FIG. 7B, therotary head controller 11 generates the rotary head pulse S11 at thetime when the reproduction head trace returns to the lowermost end andthe track skip detector 13 generates the track skip pulse S13 at theposition of the track skip given the mark 0 in FIG. 5.

FIG. 7C is a graph of the head switch operation in the head switch 12.

FIG. 8 is a flow chart of the rotary head switch operation in the headswitch 12.

The rotary heads “A11” and “B” in the head switch 12 are switched at thetiming of generation of the rotary head pulse S11 output from the rotaryhead controller 11, while the rotary heads “1” and “2” in the headswitch 12 are switched matching with the timing of the generation of thetrack skip pulse S13 in the track skip detector 13.

For example, as exemplified in FIG. 7C, the head switch first uses therotary heads (A1, B1) (step 11 in FIG. 8). In a scanning period Q1, itscans the R1 track (positive azimuth) by the rotary head A1 (positiveazimuth).

When the rotary head A1 finishes scanning the R1 track and shifts to theR2 track, the head switch 12 switches the rotary head A1 to the rotaryhead B1 (step 13) matching with the reception of the rotary head pulseS11 from the rotary head controller 11 (FIG. 8, step 12).

In a scanning period Q2, the scanning of the R2 track (negative azimuth)is started by the rotary head B1 (negative azimuth), but a skip to an R3track (positive azimuth) occurs in the middle. The head switch 12switches the use of the rotary heads (A1, B1) to the use of the rotaryheads (A2, B2) (step 15) at the time of generation of the track skippulse S13 from the track skip detector 13 (step 15) and scans theremainder of the R3 track (positive azimuth) by the rotary head B2(positive azimuth).

In a scanning period Q3, an R4 track (negative azimuth) is scanned bythe rotary head A2 (negative azimuth). In a scanning period Q4, an R5track (positive azimuth) is scanned by the rotary head B2 (positiveazimuth).

In a scanning period Q5, an R6 track (negative azimuth) is scanned bythe rotary head A2 (negative azimuth), a switch is made to the use ofthe rotary heads (A1, B1) matching with the generation of the track skippulse S13, and an R7 track (positive azimuth) is scanned by the rotaryhead A1 (positive azimuth).

The head switch 12 repeats the above operations. Note that, along withthe switching of the rotary heads in the head switch 12, a pulse-likenoise is sometimes generated. This noise is one of the anomalous signalsof the present invention.

Due to the above operation, the head switch 12 transmits the detectionsignals of the rotary heads A1, A2, B1, and B2 compatible with theoperation (scanning) of the rotary heads A1, A2, B1, and B2 at the timeof high speed reproduction to the FM demodulator 14.

The FM demodulator 14 demodulates the audio signals transmitted from thehead switch 12 by a well known method.

Waveform Connector (First Embodiment)

The waveform connector 15 of the first embodiment of the audio signalprocessing method of the present invention will be explained byreferring to FIG. 9 to FIG. 11 and FIG. 12 to FIG. 18.

FIG. 9 is a view of the configuration of the waveform connector 15.

FIG. 10 is a view of the processing of the signal buffer 152.

FIG. 11 is a flow chart of the processing of a signal processor 155.

FIG. 12 to FIG. 18 are views of the waveforms of the signals processedat the waveform connector.

The waveform connector 15 is a waveform connector utilizing the trackskip pulse S13 generated in the track skip detector 13. The track skiptime becomes clear from the track skip pulse S13, so the waveformconnector 15 connects the waveform by utilizing this.

The waveform connector 15 illustrated in FIG. 9 has an A/D converter151, a signal buffer 152, a D/A converter 154, and a signal processor155.

When the audio signal is input in a digital format, the A/D converter151 and the D/A converter 154 are unnecessary.

The A/D converter 151 converts an analog audio signal S14 demodulated atthe FM demodulator 14 shown in FIG. 12 to a digital audio signal.

Signal Buffer

As illustrated in FIG. 10, the signal buffer 152 comprises a for example16-bit signal buffer and a 1-bit anomaly flag located at a positioncorresponding to the position of the audio signal to be stored. Thecontent of the signal buffer 152 is shifted rightward every samplingtime. New data is added to the input position and the data at the outputposition is output. The audio signal stored in the signal buffer 152 isstored in time series, so the storage position of the audio signalcorresponds to the time. The output position and the processing centerposition do not vary, but the input position varies in accordance withthe time discrepancy due the processing of the signal processor.

The D/A converter 154 converts the digital audio signal output from thesignal buffer 152 to an analog audio signal.

Signal Processor

The signal processor 155 illustrated in FIG. 9 has a buffer controller1551, an anomaly deleter 1552, a waveform connector 1553, a pseudowaveform generator 1554, a time discrepancy storage 1555, and a pseudowaveform detector 1556.

The signal processor 155 monitors the existence of generation of thetrack skip pulse S13 and performs a series of processing of anomaloussegment deletion, waveform connection, and pseudo waveform insertionwhen an anomalous state arises in the waveform due to the generation ofthe track skip pulse S13.

Buffer Controller

The buffer controller 1551 concludes that there is an anomaly in thewaveform of the audio signal when there is a reception of the track skippulse S13 and sets the anomaly flag portion in the signal buffer 152corresponding to that time at “1”.

FIG. 12 is a waveform diagram of an audio signal S141 output from theA/D converter 151 to the signal processor 155. Assume that an anomalousportion exists in a period T. The period T indicates the center time ofthe processing of the signal buffer 152.

The buffer controller 1551 further exchanges the audio signal processedin the waveform connector 1553, pseudo waveform generator 1554, timediscrepancy storage 1555, and pseudo waveform detector 1556 with thesignal buffer 152 to shift and replace the data in the signal buffer 152along with the series of processing.

Anomaly Deleter

The anomaly deleter 1552 deletes the signal of the anomalous portion.

FIG. 13 is a signal waveform diagram of the case where the anomalousportion is deleted from the signal waveform illustrated in FIG. 12 bythe anomaly deleter 1552.

W represents a deletion time width (deleted segment length), TSrepresents a deletion start time, and Te represents a deletion end time.

Details of the deletion time width (deleted segment length) W, deletionstart time TS, and deletion end time Te will be explained later. Thedeleted segment length W may be set longer than the maximum time lengthof the shot noise. It is set at for example 20 ms in the case of shotnoise, and while is set at for example 5 ms in the case of discontinuityor signal skip.

Waveform Connector

The waveform connector 1553 overlaps and connects the waveform beforeand after the deleted segment illustrated in FIG. 13 to give a maximumsimilarity. The similarity is evaluated according to a mutualcorrelation coefficient.

The waveform of the input audio signal is defined as f(t) and thewaveform in the forward direction of the deleted segment is representedby the following equation 1.

$\begin{matrix}{{f_{a}(t)} = \left\{ {{\begin{matrix}{f(t)} \\0\end{matrix}\begin{matrix}\left( {t \leqq T_{s}} \right) \\\left( {t > T_{s}} \right)\end{matrix}},} \right.} & (1)\end{matrix}$

The waveform in back of the deleted segment is represented by thefollowing equation 2.

$\begin{matrix}{{f_{b}(t)} = \left\{ {\begin{matrix}0 & \left( {t < T_{e}} \right) \\{f(t)} & \left( {t \geqq T_{e}} \right)\end{matrix},} \right.} & (2)\end{matrix}$

As illustrated in FIG. 14, when superposed on each other by exactly alength p, the mutual correlation coefficient of the superposed portionsbecomes as shown in the following equation 3.

$\begin{matrix}{{R(p)} = \frac{\int_{0}^{p}{{f_{a}\left( {t + T_{s} - p} \right)}{f_{b}\left( {t + T_{e}} \right)}\ {\mathbb{d}t}}}{\sqrt{\int_{0}^{p}{{f_{a}^{2}\left( {t + T_{s} - p} \right)}\ {\mathbb{d}t}{\int_{0}^{p}{{f_{b}^{2}\left( {t + T_{e}} \right)}\ {\mathbb{d}t}}}}}}} & (3)\end{matrix}$

This processing corresponds to calculation of the correlation byshifting the waveform in back of the deleted segment forward by exactlya length (p+W). That is calculated within a range of p_(min)≦p≦p_(max).The time difference p giving the maximum correlation coefficient isdetermined as an overlap segment length P.P={p|R(p)→maximum, p _(min) ≦p≦p _(max)}  (4)

Here, the search range of P is made about the same degree as one pitchperiod of the speech or music (audio signal). For example, P_(min)=4 msand P_(max)=20 ms are set.

After the overlap segment length is determined, as shown in FIG. 15, thefront and back waveform are superposed over the segment P and crossfaded.

$\begin{matrix}{{g(t)} = \left\{ \begin{matrix}{f_{a}(t)} & \left( {t \leqq T_{q}} \right) \\{\left\{ {{\left( {T_{s} - t} \right){f_{a}(t)}} + {\left( {t - T_{q}} \right){f_{b}\left( {t + W} \right)}}} \right\}/P} & \left( {T_{q} < t < T_{s}} \right) \\{f_{b}\left( {t + W} \right)} & \left( {t \geqq T_{s}} \right)\end{matrix} \right.} & (5)\end{matrix}$

Note that, Tq=Ts−P.

Due to this method, the followings are realized:

1. Sound having periodicity in the waveform like speech (vowels) ormusic usually has the maximum correlation in that period or a wholemultiple of the same, so can be connected while maintaining theperiodicity.

2. Even if not a periodic waveform, it can be connected by the portionhaving the highest correlation, that is, similar in waveform.

3. Due to the cross fading, it can be smoothly connected withoutdiscontinuity in the waveform.

Time Discrepancy Storage and Pseudo Waveform Generator

According to the above processing, the waveform is shortened by (W+P)time for each anomaly. Therefore, if left as it is, the discrepancybetween the original sound and the processed sound will accumulate.Therefore, the cumulative time discrepancy from the point of time ofstart of the processing is stored in the time discrepancy storage 1555.When the waveform is shortened by a constant value or more, a shortpseudo waveform is prepared in the pseudo waveform generator 1554 andinserted to thereby stretch the total length.

As shown at step 31 of FIG. 11, first, at the start of the processing,the time discrepancy storage 1555 resets the cumulative time discrepancystored. The time discrepancy storage 1555 subtracts (X+P) from thecumulative time discrepancy stored at step 38 whenever the anomalyprocessing is carried out at steps 33 to 37. When the time discrepancystorage 1555 detects that the cumulative time discrepancy exceeds a setvalue during the processing (step 39), the pseudo waveform detector1556, the pseudo waveform generator 1554, and the waveform connector1553 perform the pseudo waveform detection processing, pseudo waveformgeneration processing, and the pseudo waveform insertion processingshown at steps 40 to 42. This set value may be for example 0 second. Inthat case, the waveform is always stretched in the initial processingand the signal is adjusted to maintain a slightly longer time than theoriginal sound.

The pseudo waveform generation and insertion processing will beexplained below. An example of the waveform after the waveformconnection processing is shown in FIG. 16.

First, a waveform having a length l is taken in the front of thefrontmost portion Tq of the connection point, and the mutual correlationcoefficient with the waveform further in front from that by a length lis calculated.

$\begin{matrix}{{R(l)} = \frac{\int_{0}^{l}{{g\left( {t + T_{q} - l} \right)}{g\left( {t + T_{q} - {2l}} \right)}\ {\mathbb{d}t}}}{\sqrt{\int_{0}^{l}{{g^{2}\left( {t + T_{q} - l} \right)}\ {\mathbb{d}t}{\int_{0}^{l}{{g^{2}\left( {t + T_{q} - {2l}} \right)}\ {\mathbb{d}t}}}}}}} & (6)\end{matrix}$

This is calculated over a segment of l_(min)≦1≦l_(max). The 1 whichbecomes the maximum is determined as the pseudo waveform time length L.L={l|R(1}→maximum, l _(min)≦1≦1_(max)}  (7)

Here, the search range of the length l is made about the same degree asone pitch period of speech or music in the same way as the waveformconnection portion. For example, l_(min) is made 4 ms and l_(max) ismade 20 ms.

After the pseudo waveform time length L is determined, as shown in FIG.17, the waveform is divided at the time Tl=Tq−L. The back waveform ismoved back by exactly L. When the front waveform is ga (t) and the backwaveform after the movement is ga(t), they can be represented as followsby using g(t) of equation 5.

$\begin{matrix}{{g_{a}(t)} = \left\{ {\begin{matrix}{g(t)} \\0\end{matrix}\begin{matrix}{\left( {t \leqq T_{l}} \right),} \\{\left( {t > T_{l}} \right),}\end{matrix}} \right.} & (8) \\{{g_{b}(t)} = \left\{ {\begin{matrix}0 \\{g\left( {t - W} \right)}\end{matrix}\begin{matrix}{\left( {t \leqq T_{q}} \right),} \\{\left( {t > T_{q}} \right),}\end{matrix}} \right.} & (9)\end{matrix}$

Finally, as shown in FIG. 18, a pseudo waveform prepared by cross fadingthe waveform on the two sides shown in equation 10 is inserted in thesegment Tl<t<Tq which becomes empty by the above processing,

$\begin{matrix}{{F(t)} = \left\{ \begin{matrix}{g_{a}(t)} & {\left( {t \leqq T_{l}} \right),} \\{\left\{ {{\left( {T_{q} - t} \right){g_{a}(t)}} + {\left( {t - T_{l}} \right){g_{b}(t)}}} \right\}/L} & {\left( {T_{l} < t < t_{q}} \right),} \\{g_{b}(t)} & {\left( {t \geqq T_{q}} \right),}\end{matrix} \right.} & (10)\end{matrix}$

The following can be realized by such a method.

1. Sound having periodicity in waveform like speech (vowels) or musichas the maximum correlation in a whole multiple of the period, so thewaveform is stretched while maintaining the periodicity.

2. Even if not a periodic waveform, it can be connected by the portionhaving the highest correlation, that is, similar in waveform.

3. Due to the cross fading, it can be smoothly connected withoutdiscontinuity in the waveform.

Time Discrepancy Storage

The time discrepancy storage 1555 stores the shortened time from thestart of the processing and the cumulative time of the extension.

The series of operation of the waveform connector 15 will be explainednext by referring to FIG. 11.

Step 31: Before storing the audio signal in the signal buffer 152, asthe initial operation, the buffer controller 1551 in the signalprocessor 155 resets the cumulative time discrepancy storage data.

Step 32: The analog audio signal S14 illustrated in FIG. 12 demodulatedin the FM demodulator 14 is converted to a digital audio signal in theA/D converter 151. The converted digital audio signal S151 issuccessively stored in the signal buffer 152 every sample time. Thesignal buffer 152 is configured by a ring buffer or FIFO. The digitaldata is given from its output end to the D/A converter 154 every sampletime and output as an output audio signal S15.

Step 33: The buffer controller 1551 decides that an anomalous stateoccurred when receiving a track skip pulse S13, sets the anomaly flag atthe position corresponding to that time in the signal buffer 152 (FIG.10), and proceeds to the processing of step 35 and the following steps.When it does not receive the track skip pulse S13, the operation routineshifts to the processing of step 34.

Step 34: When there is no anomaly, the buffer controller 1551 doesnothing. In that case, the audio signal successively stored in thesignal buffer 152 is successively output to the D/A converter 154 aftera predetermined time.

Step 35: When an anomalous state is detected at the buffer controller1551, the anomaly deleter 1552 deletes the data of the anomalous portionin the vicinity of the time T in FIG. 12 described above. Namely, whenthe anomalous state is detected, the anomaly deleter 1552 deletes thesignal before and after the processing center time as illustrated inFIG. 13. The noise, data loss, or the like to be eliminated by thepresent invention is instantaneous shot noise or discontinuity, so thedeleted segment may be made for example about 5 ms.

Steps 36 to 37: When the anomalous data is deleted, the waveformconnector 1553 connects the signal before and after the deleted segmentin cooperation with the pseudo waveform detector 1556 and the pseudowaveform generator 1554.

The pseudo waveform detector 1556 searches for a similar portion byshifting the waveform data in back of the deletion portion asillustrated in FIG. 14 and overlaps and adds it so that the parts of thewaveform before and after the deleted portion resemble each other themost.

The pseudo waveform generator 1554 detects the similar waveform of thedata stored in the signal buffer 152 by utilizing the pseudo waveformdetector 1556 again in order to compensate for the portion shortened inthe total length of the data by the processing of the anomaly deleter1552 and the waveform connector 1553, generates the pseudo waveform forstretching the waveform, and inserts the generated waveform data intothe portion deleted by the anomaly deleter 1552.

Step 38: The time discrepancy storage 1555 adds and stores the timelength of the shortening/extension of the waveform by the anomalydeleter 1552, waveform connector 1553, and the pseudo waveform generator1554.

Step 39: The time discrepancy storage 1555 decides whether or not thetime discrepancy is within a constant value. When it is within theconstant value, the operation routine shifts to the processing of step34.

Steps 40 to 42: When the time discrepancy exceeds the constant value,the above processing is repeated. Namely, the similar waveform detector1556 evaluates the similarity of the waveform at a different time in thesignal buffer 152 as explained above.

Since the time discrepancy storage 1555 manages the amount of data ofthe audio signal in the deleted segment as time, so disconnection oroverlap of the audio signal is eliminated.

The above waveform connector 15 is able to delete the noise segment forshot noise superposed on the signal, signal skip, discontinuity, etc.,smoothly connect the waveform before and after the deletion, and limitthe time discrepancy from the original signal to the smallest level byinserting a pseudo waveform into the signal. Namely, the waveformconnector 15 of the present embodiment can delete noise derived fromshot noise or discontinuity of the audio signal without distorting thenormal portion, smoothly interpolate the discontinuous portion, andreduce incongruity in sound.

Further, the Hi-Fi video apparatus 1 of the embodiment of the presentinvention illustrated in FIG. 1 generates an audio signal compensatedfor discontinuity even in the case where there is a discontinuity of theaudio signal due to a track skip at the time of high speed reproductionor switching of the rotary head sat the head switch 12 and as a resultcan reproduce an audio signal without concern as to discontinuity.

SECOND EXAMPLE OF HI-FI VIDEO APPARATUS

A second example of the Hi-Fi video apparatus of the present inventionwill be explained by referring to FIG. 19 to FIG. 20.

The Hi-Fi video apparatus 1A of the second example has a rotary headcontroller 11, head switch 12, track skip detector 13, FM demodulator14, waveform connector 15A, a rotary head drum 16 illustrated in FIG. 2,a fixed head 17 illustrated in FIG. 2, a not illustrated rotation drivecontroller of the rotary head drum 16, a not illustrated running drivecontroller of the magnetic tape 18, a not illustrated audio signalreproducing apparatus, and a not illustrated video signal reproducingapparatus.

The Hi-Fi video apparatus 1A illustrated in FIG. 19 has a similarconfiguration to that of the Hi-Fi video apparatus 1 illustrated in FIG.1, but the track skip pulse S13 is not output from the track skipdetector 13 to the waveform connector 15An and the configuration of thewaveform connector 15A is different from that of FIG. 9 as illustratedin FIG. 20. The other portions are similar to those of the Hi-Fi videoapparatus 1 of FIG. 1, however. Accordingly, the following descriptionwill be made focusing on portions different from the first example.

Waveform Connector

The waveform connector 15A will be explained by referring to FIG. 20.

The waveform connector 15A has an A/D converter 151, signal buffer 152,D/A converter 154, signal processor 155A, and anomaly detector 156. Whenthe audio signal is input in a digital form, the A/D converter 151 andthe D/A converter 154 are unnecessary.

The waveform connector 15A does not use a track skip pulse S13 generatedin the track skip detector 13 unlike the waveform connector 15 of FIG.9. For this reason, the anomaly detector 156 is provided in the waveformconnector 15A, and the processing of the signal processor 155A isslightly different from the processing of the signal processor 155illustrated in FIG. 9.

Anomaly Detector

FIG. 21 is a view of the configuration of the anomaly detector 156.

The anomaly detector 156 has a high pass filter 1561, a power detector1562, a mean value calculator 1563, and a power comparator 1564.

The anomaly to be eliminated by the present invention is short time shotnoise or signal loss, short time signal skip (so-called sound skip), ordiscontinuity due to track skip, the switching of the rotary heads, etc.At the time of detection of an anomaly, the fact that a high frequencycomponent is instantaneously largely generated due to the nature of theshot noise or skip is utilized. For example, in speech or music, thecomponent up to about 10 kHz at most is dominant, but in contrast, inshot noise, a component up to near the Nyquist frequency isinstantaneously generated.

The high pass filter 1561 passes the high frequency component of anaudio signal S151 output from the A/D converter 151 therethrough. Thepower detector 1562 calculates the power of the signal passed throughthe high pass filter 1561, that is, the square of the signal passedthrough the high pass filter 1561. The mean value calculator 1563calculates the mean value of the power over for example past 50 ms ofthe audio signal of the high frequency component. The power comparator1564 compares the mean value of the power calculated at the mean valuecalculator 1563 and the power of the audio signal calculated at thepower detector 1562. When the power value is larger than the mean powervalue, the time is detected as the time of generation of instantaneousnoise or a skip.

FIG. 12 illustrates an example of a waveform having an anomalous portiondue to the disturbance of the waveform on the periphery of the time T.When the audio signal behaves as in the period T of FIG. 12, the valuedeviates from the mean value of the audio signal, so the anomalous statecan be detected at the power comparator 1564.

The anomalous state detected at the anomaly detector 156 is notified tothe signal buffer 152 illustrated in FIG. 10. The signal buffer 152 setsthe anomaly flag in the corresponding data.

The signal buffer 152 is similar to the signal buffer 152 explainedabove. Namely, as illustrated in FIG. 10, it comprises for example a16-bit signal buffer and a 1-bit anomaly flag. The content of the signalbuffer 152 is shifted rightward every sample time. New data is added tothe input position and the data at the output position is output. Theoutput position and the processing center position do not vary, but theinput position varies in accordance with the time discrepancy due theprocessing of the signal processor.

In the present example, the anomaly flag is set in accordance with notthe track skip pulse S13, but the detection of the anomaly detector 156.

Signal Processor

The signal processor 155A illustrated in FIG. 20 has a buffer controller1551A, anomaly deleter 1552, waveform connector 1553, pseudo waveformgenerator 1554, time discrepancy storage 1555, and pseudo waveformdetector 1556.

The signal processor 155 monitors the anomaly flag stored in the signalbuffer 152 by the anomaly detector 156, performs no operation where theanomaly flag is “0” (where there is no anomaly), and performs a seriesof processing of anomalous segment deletion, waveform connection, andpseudo waveform insertion where the anomaly flag is “1” (where there isan anomaly).

FIG. 22 is a flow chart of the processing of the signal processor 155A.

Buffer Controller

The buffer controller 1551A monitors the anomaly flag at the processingcenter for the data stored in the signal buffer 152 illustrated in FIG.10. Namely, the track skip pulse S13 is not input to the buffercontroller 1551A, so the set state of the anomaly flag set by theanomaly detector 156 is achieved by the buffer controller 1551A.Accordingly, the decision of the anomaly by the buffer controller 1551Aof step 33A in FIG. 22 becomes the monitoring of the set state of theanomaly flag of the signal buffer 152.

The buffer controller 1551A further shifts and replaces the data in thebuffer along with the series of processing for the signal with thewaveform shown in FIG. 12 to FIG. 18.

Anomaly Deleter, Waveform Connector, Pseudo Waveform Generator, TimeDiscrepancy Storage

The anomaly deleter 1552, waveform connector 1553, pseudo waveformgenerator 1554, and time discrepancy storage 1555 perform similarprocessing to that explained above by referring to FIG. 9.

As explained above, the waveform connector 15 of FIG. 9 and the waveformconnector 15A of FIG. 20 are different in only the method of detectionof the anomalous state. Accordingly, the waveform connector 15A of FIG.20 can perform similar waveform connection processing to that of thewaveform connector 15 of FIG. 9.

As a result, the Hi-Fi video apparatus 1A illustrated in FIG. 19,similar to the Hi-Fi video apparatus 1 of FIG. 1, can perform signalprocessing to eliminate anomalous due to track skip, switching of therotary heads, or the like. Namely, the Hi-Fi video apparatus 1A usingthe waveform connector 15A illustrated in FIG. 19 generates an audiosignal compensated for anomaly even when there is an anomaly of theaudio signal due to track skip at the time of high speed reproductionand the switching of the rotary heads in the head switch 12 and as aresult can reproduce an audio signal without concern as to anomaly.

THIRD EXAMPLE OF HI-FI VIDEO APPARATUS

The method of detection of the anomalous portion in the waveformconnectors 15 and 15A is not limited to the examples explained above.Other various methods can be employed.

For example, in the same way as a track skip being detected at the trackskip detector 13 and a track skip pulse S13 being output to the waveformconnector 15, a signal indicating an anomalous state in the apparatususing the waveform connector 15 from that apparatus and an auxiliarysignal can be input to for example the buffer controller 1551 of thesignal processor 155 illustrated in FIG. 9.

As such an auxiliary signal, use can be made of for example an errorcorrection code used at the time of reproduction of a CD etc. By this,the time of generation of the anomaly becomes clear, and the processingin the waveform connector 15 becomes possible.

The waveform connectors 15 and 15A can be applied to not only a Hi-Fivideo apparatus, but also various other apparatuses handling audiosignals. As such apparatuses, there are for example CD audio signalplayers, MD players, DVD players, cellular phones, 8 mm videoapparatuses, and audio signal communication devices.

When the present invention is applied to such apparatuses, even if thereis noise or skips due to scratches or dust on the magnetic tape, noiseor skips due to scratches or dust on the magnetic disk, noise or skipsdue to scratches or dust on the optical disk, noise or skips due toscratches or dust on the analog record disk, noise or signal lossoccurring in the air or apparatus, etc., the influence of them can beeliminated and the incongruity in sound can be reduced.

Further, the present invention is not limited to the Hi-Fi videoapparatuses explained above and can be applied to the signal processingof an anomaly caused when reproducing an audio signal recorded on amagnetic tape or a rotary recording medium such as a magnetic disk.

Digital Video Signal Recording and/or Reproducing Apparatus

As another embodiment of the present invention, a digital video signalrecording and/or reproducing apparatus will be explained. Theexplanation of the processing in the Hi-Fi video apparatuses alsoapplies to a digital video signal recording and/or reproducingapparatus, but a Hi-Fi video apparatus and digital video signalrecording and/or reproducing apparatus have the following differences.

1. A digital video signal recording and/or reproducing apparatus iscontrolled to follow a track by a dynamic tracking head even at the timeof high speed reproduction, so skips occur also in units of tracks.

2. A digital video signal recording and/or reproducing apparatus caneasily judge a track skip since an ID is recorded at the track head.

FIG. 23 is a view of the configuration of a digital video signalrecording and/or reproducing apparatus 2 taking into account the aboveconditions.

The digital video signal recording and/or reproducing apparatus 2 has anot illustrated rotary drum with rotary heads An and B mounted thereon,a digital signal demultiplexer 21, a track skip detector 22, and awaveform connector 23.

FIG. 24 is a view of the track structure of the recording surface of aconsumer-use digital video tape, and FIG. 25 is a view of the headscanning trace at the time of high speed reproduction.

In this example, the tracks are read skipping one out of three tracks.

The rotary heads An and B are arranged facing each other at 180 degreesin the same way as illustrated in FIG. 2, but the digital video signalrecording and/or reproducing apparatus is controlled to scan along atrack by a not illustrated auto tracking control mechanism.

The digital signal demultiplexer 21 reads a recording signal comprisedby insert and track information (ITI), an audio signal, a video signal,and a sub code and demultiplexes the same as the digital data.

The digital signal demultiplexer 21 transmits the video signal to a notillustrated usual video processor and transmits the audio signal to thewaveform connector 23.

The digital signal demultiplexer 21 inputs the head signal to the trackskip detector 22.

The track skip detector 22 detects the ID number of the track from thehead signal, compares the same with the ID number of the trackreproduced immediately before that, and determines the existence of atrack skip. The track skip detector 22 sets “0” when the ID numberscontinue, while sets “1” when they do not continue, and transmits atrack skip pulse S22 to the waveform connector 23.

The waveform connector 23 has a similar configuration to that of thewaveform connector 15 illustrated in FIG. 9 as illustrated in FIG. 26.

The waveform connector 23 is configured by a signal buffer 231 and asignal processor 232. The signal processor 232 is configured by a buffercontroller 2321, an anomaly deleter 2322, a waveform connector 2323, apseudo waveform generator 2324, a time discrepancy storage 2325, and apseudo waveform detector 2326.

The signal buffer 231 of the waveform connector 23 corresponds to thesignal buffer 152 of the waveform connector 15. The signal processor 232of the waveform connector 23 corresponds to the signal processor 155 ofthe waveform connector 15. The buffer controller 2321, anomaly deleter2322, waveform connector 2323, pseudo waveform generator 2324, timediscrepancy storage 2325, and pseudo waveform detector 2326 correspondto the buffer controller 1551, anomaly deleter 1552, waveform connector1553, pseudo waveform generator 1554, time discrepancy storage 1555, andpseudo waveform detector 1556.

Note that the digital video signal recording and/or reproducingapparatus 2 performs digital signal processing, so the A/D converter 151and the D/A converter 154 are not provided.

The signal buffer 231 receives as input a digital audio signal S21Adetected and demultiplexed at the digital signal demultiplexer 21.

The buffer controller 2321 performs processing equivalent to thedecision processing at step 33 of FIG. 11 when the track skip pulse S22is “1”.

The buffer controller 2321, anomaly deleter 2322, waveform connector2323, pseudo waveform generator 2324, time discrepancy storage 2325, andpseudo waveform detector 2326 perform similar processing to that of thebuffer controller 1551, anomaly deleter 1552, waveform connector 1553,pseudo waveform generator 1554, time discrepancy storage 1555, andpseudo waveform detector 1556 explained above.

As explained above, the digital video signal recording and/orreproducing apparatus 2 can repair an audio signal having an anomaly dueto a track skip or the like even in the case of high speed reproductionin the same way as a Hi-Fi video apparatus.

8 mm Video Apparatus

The present invention can also be easily applied to an 8 mm videoapparatus.

The track structure of an 8 mm video tape is shown in FIG. 27.

An audio signal is digitally recorded on the magnetic tape by a rotaryhead as a PCM audio signal. An FM modulated analog signal (in the sameway as a Hi-Fi signal) is recorded multiplexed on the video signal.

When the 8 mm video apparatus uses an FM audio signal using a dynamictracking head, the processing is the same as in a Hi-Fi video apparatus.Further, when the 8 mm video apparatus uses a PCM audio track using thedynamic tracking head, a similar configuration to that of the case ofthe digital video apparatus is employed.

In this way, the 8 mm video apparatus can utilize the audio signal of aPCM or FM track at the time of high speed reproduction.

Magnetic Disk Apparatus

The data skip in the case of a magnetic disk apparatus has the followingcharacteristic features unlike a track skip in a Hi-Fi video apparatusor a digital video signal recording and/or reproducing apparatusexplained above.

1. The random accessibility of the data is high, so a skip due tolimitations of physical arrangement of the tracks on a tape does notoccur.

2. Rather, at the time of high speed reproduction, there are datasegments which are intentionally not read so as to keep the data withinthe readable speed.

FIG. 28 is a view of the hardware configuration of a magnetic diskapparatus taking into account the above circumstances.

The magnetic disk apparatus 3 has an address controller 31, a fixed diskdrive 32, and a waveform connector 33.

The fixed disk drive 32 stores the audio signal and the video signals asdigital data. At the time of reproduction, the data is read according tothe address designated by the address controller 31 and input to thewaveform connector 33.

The address controller 31 compares the reproduction speed designated bythe user and the reading speed of the fixed disk, determines the dataread segments and the nonread segments so as to be within the range ofthe read speed, and designates the read addresses to the fixed datadrive 32 accordingly. Further, it generates a data skip signal at theend of continuous read segments (immediately before a nonread segment)and inputs the same to the waveform connector 33.

FIGS. 29A, 29B, 29C, and 29D are graphs of the operation timing of themagnetic disk apparatus 3.

For convenience, assume that successive recording data (FIG. 29A) givennumbers D1 to D15 are recorded in the fixed disk drive 32.

At the time of reproduction, assume that the address controllerdetermines the read segments and the nonread segments as illustrated inFIG. 29B. At that time, the data actually read from the fixed disk drive32 become as illustrated in FIG. 29C, and discontinuity of data occursbetween D5 and D8 and between D12 and D15. The data skip signalgenerated by the address controller 31 detecting such discontinuitybecomes as shown in FIG. 29D.

The waveform connector 33 has the equivalent circuit configuration tothe waveform connector 23 illustrated in FIG. 26.

Accordingly, the waveform connector 33 receiving the data skip signalfrom the address controller 31 performs repair processing similar tothat explained above for the audio signal input from the fixed diskdrive 32.

As explained above, the present invention is not limited to the highspeed reproduction of an audio signal recorded on a recording mediumlike a magnetic tape and can be applied to also the high speedreproduction of an audio signal recorded on a random access typerecording medium such as a magnetic disk and an optical disk.

Further, the present invention is not limited to the embodimentsexplained above. The present invention can be applied to various othertypes of audio signal processing apparatuses. As such audio signalprocessing apparatuses, there are the compact disk players, MD players,DVD players, etc.

The present invention can not only be applied to apparatuses such asHi-Fi video apparatuses, digital video signal recording and/orreproducing apparatuses, 8 mm video apparatuses, and magnetic diskapparatuses, but also can use elements configuring these apparatusesalone.

For example, the waveform connectors 15, 23, and 33 shown in the variousembodiments are not limited to the waveform connection of the audiosignals explained above, but can also be applied to other signalprocessing.

Summarizing the effects of the present invention, the audio signalprocessing method and the audio signal processing apparatus of thepresent invention delete the audio signal in the noise segment due toshot noise superposed on the signal, signal skip, and discontinuity andsmoothly connect the waveform before and after the deletion.Particularly, it can keep the time discrepancy from the original audiosignal to a minimum level by inserting a pseudo waveform into thesignal.

The audio signal processing apparatuses such as Hi-Fi video apparatuses,digital video signal recording and/or reproducing apparatuses, 8 mmvideo apparatuses, and magnetic disk apparatuses can reproduce a highquality audio signal with little incongruity by eliminating theinfluence of the sound skip (skip) occurring at the time of high speedreproduction, the noise at the switching of the heads, etc.

As a result, for example, in a Hi-Fi video apparatus, even when tryingto save time while fully viewing and listening to the content byreproduction at 1.2× speed, a high quality audio signal can bereproduced. In a magnetic disk apparatus, it becomes possible to obtaina greater margin in the access time and therefore perform time divisionprocessing with other tasks without exceeding the limit of the accesstime.

1. An audio signal processing apparatus, comprising: a signal deletingmeans for deleting an audio signal in an anomalous segment, a deducingmeans for deducing a correct audio signal by referring to a waveform ofthe audio signal before and after said deleted segment; a repair signalgenerating means for generating a repair signal for repairing the signalof said deleted segment based on said deduced result; a signalconnecting means for inserting said repair signal into said deletedsegment and connecting said repair signal with the audio signal beforeand after the deleted segment; and anomaly detecting means for detectingan anomalous state of the audio signal and performing said processingwhen detecting said anomalous state, said anomalous state detectingmeans detecting said anomalous state by detecting skip scanning of areading means when reading an audio signal from a recording medium,wherein said recording medium comprises a randomly accessible rotaryrecording medium, said reading means comprises a head able to randomlyaccess said rotary recording medium, and said anomalous state is judgedby detecting a time of skip operation of said head.